Apparatus, method and system for determining the integrity of sealed containers

Abstract

A method, apparatus and system for determining the integrity of a container sealed by means of a closure comprising a resilient sealing element and a cup-like cap having a top and a depending skirt compressing the resilient sealing element over the discharge opening in the container. The invention consists of verifying seal integrity by applying an external force to the cap and measuring the force required to effect initial movement thereof to overcome the residual static force in the resilient sealing element and by comparing the measured force which is essentially equal to the residual static force in the resilient sealing element to a predetermined standard known to provide an acceptable seal. It is known that when the force between the crimped edge of the cap and the container is zero which occurs upon initial displacement of the cap relative to the container, the externally applied force is essentially equal to the residual static force in the resilient sealing element. The residual static force in the resilient sealing element is measured by apparatus including a mechanical force applicator unit having an anvil engageable with the cap mounted on an actuator member of a gauge for measuring the applied force and a microscope, for observing initial downward displacement of the cap when a given external force essentially equal to the residual static force in the resilient sealing element is applied.

What is claimed is: 
     
       1. A method for testing the integrity of the seal of a container sealed by means of a closure comprising a resilient sealing element and a mechanical element compressing said resilient sealing element and locking the same in sealed relationship to said container which comprises: applying an external force to said mechanical element in a direction to further compress said resilient sealing element,   sensing displacement of said mechanical element relative to said container when said externally applied force is substantially equal to the initial residual static force in said compressed resilient sealing element, and comparing the said residual static force so determined to a predetermined standard known to indicate sufficient compression of said resilient sealing element to provide an acceptable seal.   
     
     
       2. Apparatus for testing the integrity of a container B sealed by means of a closure comprising a resilient sealing element S and a cup-like cap (C) having a top and a depending skirt compressing said sealing element over the discharge opening in the container comprising means for applying an external force to the cap in a direction to further compress said resilient sealing element, and indicia means to detect initial displacement of said cap relative to said container when the externally applied force exceeds the residual static force in said sealing element. 
     
     
       3. Apparatus as claimed in claim 2 wherein said indicia means includes a microscope. 
     
     
       4. Apparatus as claimed in claim 2 wherein said indicia means comprises a collar made of a flexible material filled with an incompressible fluid supported in a position adjacent the cap and a capillary tube partially filled with said fluid in communication with said collar whereby displacement of said cap effects compression of said collar and displacement of said fluid in said capillary tube. 
     
     
       5. A system for testing the integrity of a container sealed by means of a closure comprising a resilient sealing element and a cap having means for seating the sealing element over the opening of the container to firmly hold said sealing element with a predetermined residual static force against the container comprising a force guage including means for applying an external force to the cap in a direction to further compress said resilient sealing element, means for detecting the initial displacement of said cap relative to the container when the external force slightly exceeds the residual static force in the sealing element and means for determining the applied force. 
     
     
       6. A method as claimed in claim 1 including sensing displacement of said mechanical element at various locations about the periphery thereof.